Solid-state drives (“SSDs”) are yet another step towards greener stable-storage technologies. SSDs are data storage devices using solid-state memory to store persistent data. An SSD emulates a hard disk drive interface, thereby making an SSD a replacement for a hard disk drive interface. An SSD using flash memory is known as a flash drive. An SSD using SRAM or DRAM (instead of flash memory) is often called a random access memory (“RAM”)-drive. Dynamic random access memory (“DRAM”)-based SSDs usually incorporate either an internal battery or an external AC/DC adapter and backup storage systems to ensure data persistence while no power is being supplied to the drive from an external source. If power is lost, the battery provides power while all information is copied from RAM to back-up storage. When the power is restored, the information is copied back to the RAM from the back-up storage, and the SSD resumes normal operation.
Being nascent in a market rejuvenated by green, virtualization, performance considerations, SSDs also find use in companion virtualization as a mutual enabler for mirroring memory and file/disk-state of systems. Hence, numerous opportunities to innovate arise, such as addressing disaster recovery (“DR”) by enhanced means unique to the SSD environment. Usually, enterprise-class SSDs are SRAM-backed (e.g., by the SSD sold by Fusion-io™ under the tradname ioDrive Duo™) in turn backed by low-power/low-cost batteries (e.g., on-board rechargeable button cells on the SSD unit). Uses for such SSDs include as main memory with stable-store to back up against power-outages and for real-time backup of filesystems or highly dynamic system states and filesystems.